Air Toxics
of Greatest Concern in New England - 2005 NATA

The 2005 National Air Toxics Assessment (NATA)
estimated that state average risk values of five air toxics: acetaldehyde, benzene, carbon tetrachloride, formaldehyde, and polycyclic organic matter (POM) exceeded health benchmarks in every state in New England, and state average risk values of five air toxics: 1, 3-butadiene, acrolein, arsenic compounds, chromium compounds and naphthalene exceeded health benchmarks in at least one state in New England. Diesel particulate matter is also an air toxic of concern since the estimated ambient concentrations are high in most of the New England states. Most of these chemicals are carcinogens and may also cause other health effects, such as exacerbation of asthma. County level average risk values of perchloroethylene exceeded health benchmarks in several counties in New England and may be more of a health concern at the local level rather than at the regional level.

The risk values used in 2005 NATA represent the concentration of a pollutant above which there may be potential public health concerns. The risk values essentially serve as "yardsticks" to assess the potential threat to the public health posed by the Clean Air Act Hazardous Air Pollutants (HAPs) which have established risk values. These values represent the current state of scientific understanding about the health effects of the pollutants of concern. The upper-bound lifetime cancer risk value denotes the concentration of a known, probable or possible human carcinogen that will result in the potential for one excess cancer to occur in one million individuals exposed over a 70 year lifetime.

Background concentrations represented an overwhelming portion of the ambient concentrations derived for carbon tetrachloride because it persists in the environment and so we have not analyzed these emissions in great detail but have included it on our list of greatest concern. Background sources also account for a significant portion of the ambient concentrations for 1,3-butadiene, arsenic compounds, benzene, and chromium compounds, but are also emitted from various sources and so, we have analyzed these emissions. Atmospheric transformation (secondary formation) accounts for a significant portion of the ambient air concentration for acetaldehyde, acrolein and formaldehyde, but are also emitted from various sources and so, we have analyzed these emissions.

NATA evaluated the inhalation route of exposure for toxic air pollutants that had established health risk values and outdoor air emission estimates. Therefore, there are other air toxics, such as: asbestos, dioxins, lead, mercury, radon and PCBs, that are also a concern due to other routes of exposure or exposure from indoor sources for which Region I has developed separate risk reduction strategies.

The following Table includes information on the point,
non-point and area,
and mobile
emissions sources, health effects, and modeled ambient concentrations
for the pollutants of greatest concern in New England. The estimated risk maps are based on the air emission estimates from 2005 with assumptions that these risk levels would continue, hence, the maps may not reflect current reductions. The New England estimated risk maps still provided sufficient information for EPA Region I to prioritize the air toxics of greatest concern.

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Summation of Carcinogenic Risk Estimate Map of New England

The map below represents a summation of carcinogenic risk estimates for inhalation exposure to 80 air toxics that have been modeled in the 2005 National Scale Air Toxic Assessment. The risk estimates in the map below are based on the census tract level average of a typical individual's exposure.

The following limitations to these carcinogenic risk estimates for exposure
to these air toxics must be noted: the inhalation route of exposure is
the only exposure route that has been evaluated, only inventoried outdoor
air toxic sources were used in this assessment since there isn't adequate
data on indoor air exposures, and the risks associated with each carcinogenic
pollutant are only added together since there is inadequate information
on other health effect interactions.

These carcinogenic risk estimates can not be related to an individual's
risk of cancer because the estimates are restricted to 2005 estimates
and the results should be reviewed across broad geographic areas such as counties and states.
These risk estimate maps should not be used to obtain information on
specific types of cancers or possible cancer clusters but they can provide
EPA, the states and the public with information on whether we're focusing
on the right pollutants and sources to protect the public health.

Summation of Noncancer Risks Map of New England

The map below represents a summation of hazard quotients that are used to provide a quantification of risks associated with noncarcinogenic chronic health effects for respiratory irritants. EPA considered adverse health effects other than cancer for 110 air toxics. A hazard quotient for a pollutant that is less than 1 indicates that no adverse health effects are expected as a result of exposure. If the hazard quotient is greater than 1, then adverse health effects are possible. The hazard index represented in the following map is a sum of all of the hazard quotients for the respiratory target organ system, with 43 air toxics evaluated as respiratory irritants. The risk estimates in the map are based on the census tract level average of a typical individual's exposure.

The following limitations to these chronic risk estimates must be noted:
the inhalation route of exposure is the only exposure route that has
been evaluated and only inventoried outdoor air toxic sources were used
in this assessment since there isn't adequate data on indoor air emissions.